Researchers at Georgetown University spent a month watching people ride bikes around the nation’s capital. D.C. is home to Capital Bikeshares, one of the largest programs in the U.S. The researchers noted whether cyclists were on Capital bikes or wheels of their own. They also classified riders as either casual users or likely commuters, depending on when and where the cyclists were spotted.

What they found is: bike-share riders tend to shun headgear. While 70 percent of the commuters who rode their own bikes wore helmets, fewer than a third of the bike-share commuters did the same. And the casual riders were even more lax.

To encourage helmet use, New York City, whose bike-share system is set to launch in July, is giving them away. Just show up for a fitting. It’s one way to stay a head.